The present invention relates to medical procedures in which an invasive device such as a catheter, guide wire, biopsy needle, endoscope, laparoscope or the like is inserted into a body, and more particularly concerns the tracking of such a device stereoscopically, in three dimensions, without the use of X-rays.
X-ray fluoroscopes are used routinely to monitor the placement of invasive devices during diagnostic and therapeutic medical procedures. Conventional X-ray fluoroscopes are designed to minimize X-ray dosage. Nevertheless, some procedures can be very long and the accumulated X-ray dose to the subject can become significant. The long term exposure of the attending medical staff is of even greater concern since they participate in these procedures regularly. Consequently, it is desirable to reduce the X-ray dose during these procedures.
One consequence of the need to minimize X-ray dose is the use of minimal fields-of-view. Smaller fields-of-view necessitate frequent movement of the X-ray detection system or of the subject to follow the invasive devices during a procedure. Automatic positioning of the field-of-view of the imaging system over the invasive device within may shorten the procedure and reduce the number of required personnel need to perform the procedure.
Another limitation on the use of X-ray fluoroscopes is that the technique is projective in nature and produces a single two-dimensional image. Information concerning the depth of an object within the field-of-view is not available to the operator. It is often desirable to obtain this information during invasive procedures. Stereoscopic X-ray fluoroscopes utilizing dual X-ray beams have been devised for this purpose. Dual beam X-ray systems, however, double the X-ray dose to the subject and are more complicated.